Here are some resources to aid (thanks to others on the list who have provided these resources during past events).
Disaster Distress Helpline: 1-800-985-5990
The helpline is also available in Spanish, by text and by TTY.
Talking to Children about the Shooting
Tips for Parents on explaining media coverage to children
Restoring a Sense of Safety in the Aftermath of a Mass Shooting: Tips for Parents and Professionals
Psychological First Aid for Schools Field Operations Guide
Coping with Crisis – Helping Children With Special Needs
Facing Fear: Helping Young People Deal with Terrorism and Tragic Events – for ages 5 to 7.
Activity Book for African American Families: Helping Children Cope with Crisis
After a Crisis: Helping Young Children Heal – checklist
Parent Tips for Helping Preschool-Age Children after Disasters
For the public
**Coping with Disasters
National Library of Medicine